I can't seem to find a best practice for Base64 encoding a string in Processing. 

Here is some example code which displays the error:

void setup() {
 size(250, 250);
 print("before setup() selectOutput() runs\n");
 selectOutput(); //even with this line removed, the other selectOutput() causes a problem
 print("after setup() selectOutput() runs\n");
}

void draw() {
 background(0);
 rect(mouseX, mouseY, 10, 10);  //this helps demonstrate the program ceasing to function
}

void keyPressed() {
 print("before keyPressed() selectOutput() runs\n");
 selectOutput();
 print("after keyPressed() selectOutput() runs\n");
}

In my full code, I'm catching a particular key to perform a Save As... function. When the selectOutput() during setup() runs, all is well. When the selectOutput() called by the pressed key runs, the dialog appears, you can select a file, but upon pressing Save, the sketch freezes permanently.

Any thoughts?